IEC 63267-3-61:2025

Overview

IEC 63267-3-61:2025, published by the International Electrotechnical Commission (IEC), establishes the optical interface dimensional limits for fibre optic reference connectors using physically contacting 50 μm core diameter multimode fibres. These reference connectors are terminated in non-angled, full zirconia ferrules with 2.5 mm or 1.25 mm diameters, primarily intended for reference connection applications critical to accurate attenuation measurements. The standard is applicable to A1-OM2b to A1‑OM5b multimode fibres, used in the 850 nm band, and aims to minimize measurement uncertainties in fibre-to-fibre interconnections.

IEC 63267-3-61:2025 replaces IEC 61755-6-2:2018, bringing a technical revision that introduces the definition of a new reference grade (Rm1), extends fibre type coverage, and updates test and measurement procedures.

Key Topics

• Dimensional Limits and Tolerances:
  Establishes precise tolerances for ferrule and optical interface parameters to ensure consistent, low-variation fibre connections.
• Reference Grade Rm1 Definition:
  Introduces a specific reference grade for physically contacting, non-angled, full zirconia ferrule multimode connectors.
• Attenuation Performance:
  Specifies test procedures and maximum permissible attenuation (≤0.1 dB at 850 nm) for reference connections, to ensure accuracy and repeatability in measurement setups.
• Criteria for Compliance:
  Details geometrical and physical parameters-such as endface spherical radius, apex offset, fibre undercut, and ferrule diameter-that control lateral, angular, and longitudinal alignment.
• Use of Specific Fibre Types:
  Requires use of restricted A1-OM2b to A1-OM5b multimode fibre (in accordance with IEC 60793-2-10), tightly limiting core diameter and numerical aperture for reduced variability.
• Reference Adapters:
  Outlines requirements for qualifying adapters intended for use with reference connectors, using specific attenuation measurements.
• Updates and Annexes:
  Adds informative and normative annexes covering attenuation test limits for mated reference and grade B connectors, and specifies allowable fibre undercut.

Applications

IEC 63267-3-61:2025 provides substantial value in the following areas:

• Laboratory Reference Connections:
  Used in calibration and measurement setups to ensure high-precision, repeatable insertion loss and attenuation results.
• Quality Assurance in Manufacturing:
  Supports optical connector manufacturers in controlling process variations, serving as a reference for production test fixtures.
• Installation and Field Testing:
  Enables installers and technicians to validate and certify fibre optic network performance with minimized measurement uncertainty.
• Product Development:
  Reference for design and qualification of new multimode connectors, especially where measurement repeatability and low loss are paramount.

By defining strict connector and fibre requirements, this standard supports interoperability, global compatibility, and reliability across the fibre optic industry.

Related Standards

• IEC 61754 series:
  Details interface standards for fibre optic connector types and ferrule dimensions.
• IEC 63267-2-2:
  Specifies reference connector applications and measurement principles for enhanced macrobend multimode fibres.
• IEC 60793-2-10:
  Standard covering product specifications for A1 category multimode fibres.
• IEC 61300-3-4 / 61300-3-42:
  Outline test and measurement procedures for connector attenuation and adapter qualification.
• IEC 61300-3-47:
  Addresses endface geometry inspection of spherically polished ferrules.
• IEC TR 62627-04:
  Guidance on uncertainty calculation in optical connector attenuation measurement.

Understanding and applying IEC 63267-3-61:2025 is essential for organizations involved in fibre optic component design, manufacturing, installation, or testing, ensuring consistency and precision in optical network deployments.